.\"	$OpenBSD: strcpy.3,v 1.16 2011/07/25 00:38:53 schwarze Exp $
.\"
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.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
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.Dd $Mdocdate: July 25 2011 $
.Dt STRCPY 3
.Os
.Sh NAME
.Nm strcpy ,
.Nm strncpy
.Nd copy strings
.Sh SYNOPSIS
.Fd #include <string.h>
.Ft char *
.Fn strcpy "char *dst" "const char *src"
.Ft char *
.Fn strncpy "char *dst" "const char *src" "size_t len"
.Sh DESCRIPTION
The
.Fn strcpy
and
.Fn strncpy
functions copy the string
.Fa src
to
.Fa dst
(including the terminating
.Ql \e0
character).
.Pp
The
.Fn strncpy
function copies not more than
.Fa len
characters into
.Fa dst ,
appending
.Ql \e0
characters if
.Fa src
is less than
.Fa len
characters long, and
.Em not
terminating
.Fa dst
if the length of
.Fa src
is greater than or equal to
.Fa len .
.Sh RETURN VALUES
The
.Fn strcpy
and
.Fn strncpy
functions return
.Fa dst .
.Sh EXAMPLES
The following sets
.Va chararray
to
.Dq abc\e0\e0\e0 :
.Bd -literal -offset indent
(void)strncpy(chararray, "abc", 6);
.Ed
.Pp
The following sets
.Va chararray
to
.Dq abcdef
and does
.Em not
NUL terminate
.Va chararray
because the length of the source string is greater than or equal to the
length parameter.
.Fn strncpy
.Em only
NUL terminates the destination string when the length of the source
string is less than the length parameter.
.Bd -literal -offset indent
(void)strncpy(chararray, "abcdefgh", 6);
.Ed
.Pp
The following copies as many characters from
.Va input
to
.Va buf
as will fit and NUL terminates the result.
Because
.Fn strncpy
does
.Em not
guarantee to NUL terminate the string itself, it must be done by hand.
.Bd -literal -offset indent
char buf[BUFSIZ];

(void)strncpy(buf, input, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = '\e0';
.Ed
.Pp
Note that
.Xr strlcpy 3
is a better choice for this kind of operation.
The equivalent using
.Xr strlcpy 3
is simply:
.Bd -literal -offset indent
(void)strlcpy(buf, input, sizeof(buf));
.Ed
.Sh SEE ALSO
.Xr bcopy 3 ,
.Xr memccpy 3 ,
.Xr memcpy 3 ,
.Xr memmove 3 ,
.Xr strcat 3 ,
.Xr strlcpy 3 ,
.Xr wcscpy 3 ,
.Xr wcslcpy 3
.Sh STANDARDS
The
.Fn strcpy
and
.Fn strncpy
functions conform to
.St -ansiC .
.Sh HISTORY
The
.Fn strcpy
and
.Fn strncpy
functions first appeared in
.At v7 .
